Breaking Dependence of Distributed Service Containers

ABSTRACT

Managing service container dependency is provided. A notification that a first service container is running on a host environment is received. It is determined whether the first service container is dependent on a second service container being up and running on the host environment. In response to determining that the first service container is dependent on a second service container being up and running on the host environment, it is determined whether the second service container is running on the host environment. In response to determining that the second service container is not running on the host environment, service requests from the first service container to the second service container are responded to using stub data that corresponds to the second service container.

BACKGROUND 1. Field

The disclosure relates generally to service containers distributed in ahost environment and more specifically to breaking dependence betweenservice containers distributed in the host environment during aninitialization phase using stub data running on a service containerdependency manager of the host environment.

2. Description of the Related Art

Cloud computing technology is widely used in many domains, especiallyfor distributed application deployment. Typically, application anddependent services are running on different service containers on acloud environment, called a distributed system. The dependency betweenthe different service containers of a distributed system is becomingincreasingly important for complex application deployments. Currently nosolution exists to solve the dependency between service consumercontainers and service provider containers during an initializationphase within a distributed system. For example, today a service consumercontainer will fail or keep waiting when a service provider container,which the service consumer container is dependent upon to functionproperly, is not up and running.

SUMMARY

According to one illustrative embodiment, a computer-implemented methodfor managing service container dependency is provided. A computerreceives a notification that a first service container is running on ahost environment. The computer determines whether the first servicecontainer is dependent on a second service container being up andrunning on the host environment. In response to the computer determiningthat the first service container is dependent on a second servicecontainer being up and running on the host environment, the computerdetermines whether the second service container is running on the hostenvironment. In response to the computer determining that the secondservice container is not running on the host environment, the computerresponds to service requests from the first service container to thesecond service container using stub data running on the computer thatcorresponds to the second service container. According to otherillustrative embodiments, a computer system and computer program productfor managing service container dependency are provided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a pictorial representation of a network of data processingsystems in which illustrative embodiments may be implemented;

FIG. 2 is a diagram of a data processing system in which illustrativeembodiments may be implemented;

FIG. 3 is a diagram illustrating a cloud computing environment in whichillustrative embodiments may be implemented;

FIG. 4 is a diagram illustrating an example of abstraction layers of acloud computing environment in accordance with an illustrativeembodiment;

FIG. 5 is a diagram illustrating an example of a service containermanagement system in accordance with an illustrative embodiment;

FIG. 6 is a diagram illustrating an example of a host environment inaccordance with an illustrative embodiment;

FIG. 7 is a diagram illustrating an example of a service monitor inaccordance with an illustrative embodiment; and

FIGS. 8A-8C are a flowchart illustrating a process for managing servicecontainer dependency in accordance with an illustrative embodiment.

DETAILED DESCRIPTION

The present invention may be a system, a method, and/or a computerprogram product at any possible technical detail level of integration.The computer program product may include a computer readable storagemedium (or media) having computer readable program instructions thereonfor causing a processor to carry out aspects of the present invention.

The computer readable storage medium can be a tangible device that canretain and store instructions for use by an instruction executiondevice. The computer readable storage medium may be, for example, but isnot limited to, an electronic storage device, a magnetic storage device,an optical storage device, an electromagnetic storage device, asemiconductor storage device, or any suitable combination of theforegoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a static random access memory (SRAM), a portablecompact disc read-only memory (CD-ROM), a digital versatile disk (DVD),a memory stick, a floppy disk, a mechanically encoded device such aspunch-cards or raised structures in a groove having instructionsrecorded thereon, and any suitable combination of the foregoing. Acomputer readable storage medium, as used herein, is not to be construedas being transitory signals per se, such as radio waves or other freelypropagating electromagnetic waves, electromagnetic waves propagatingthrough a waveguide or other transmission media (e.g., light pulsespassing through a fiber-optic cable), or electrical signals transmittedthrough a wire.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network may comprisecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations ofthe present invention may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, configuration data for integrated circuitry, oreither source code or object code written in any combination of one ormore programming languages, including an object oriented programminglanguage such as Smalltalk, C++, or the like, and procedural programminglanguages, such as the “C” programming language or similar programminglanguages. The computer readable program instructions may executeentirely on the user's computer, partly on the user's computer, as astand-alone software package, partly on the user's computer and partlyon a remote computer or entirely on the remote computer or server. Inthe latter scenario, the remote computer may be connected to the user'scomputer through any type of network, including a local area network(LAN) or a wide area network (WAN), or the connection may be made to anexternal computer (for example, through the Internet using an InternetService Provider). In some embodiments, electronic circuitry including,for example, programmable logic circuitry, field-programmable gatearrays (FPGA), or programmable logic arrays (PLA) may execute thecomputer readable program instructions by utilizing state information ofthe computer readable program instructions to personalize the electroniccircuitry, in order to perform aspects of the present invention.

Aspects of the present invention are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer readable program instructions.

These computer readable program instructions may be provided to aprocessor of a general purpose computer, special purpose computer, orother programmable data processing apparatus to produce a machine, suchthat the instructions, which execute via the processor of the computeror other programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks. These computer readable program instructionsmay also be stored in a computer readable storage medium that can directa computer, a programmable data processing apparatus, and/or otherdevices to function in a particular manner, such that the computerreadable storage medium having instructions stored therein comprises anarticle of manufacture including instructions which implement aspects ofthe function/act specified in the flowchart and/or block diagram blockor blocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational steps to be performed on the computer,other programmable apparatus or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof instructions, which comprises one or more executable instructions forimplementing the specified logical function(s). In some alternativeimplementations, the functions noted in the blocks may occur out of theorder noted in the Figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instructions.

With reference now to the figures, and in particular, with reference toFIGS. 1-5, diagrams of data processing environments are provided inwhich illustrative embodiments may be implemented. It should beappreciated that FIGS. 1-5 are only meant as examples and are notintended to assert or imply any limitation with regard to theenvironments in which different embodiments may be implemented. Manymodifications to the depicted environments may be made.

FIG. 1 depicts a pictorial representation of a network of dataprocessing systems in which illustrative embodiments may be implemented.Network data processing system 100 is a network of computers, dataprocessing systems, and other devices in which the illustrativeembodiments may be implemented. Network data processing system 100contains network 102, which is the medium used to provide communicationslinks between the computers, data processing systems, and other devicesconnected together within network data processing system 100. Network102 may include connections, such as, for example, wire communicationlinks, wireless communication links, and fiber optic cables.

In the depicted example, server 104 and server 106 connect to network102, along with storage 108. Server 104 and server 106 may be, forexample, server computers with high-speed connections to network 102. Inaddition, server 104 and server 106 may provide a set of servicecontainer dependency management services for breaking dependenciesbetween service containers during an initialization phase of relied uponservice containers using stub data running on server 104 and server 106.Also, it should be noted that server 104 and server 106 may eachrepresent a plurality of servers providing service container dependencymanagement services for a plurality of service container hostenvironments. A service container is an isolated environment that runsan application, which provides a service to requesting serviceconsumers. A host environment may run many service containerssimultaneously. Each service container is built from an image. The imageis a read-only template with instructions for creating a servicecontainer. Thus, the image defines the content of a service container,which process to run when the service container is booted, and a varietyof other configuration details.

Client 110, client 112, and client 114 also connect to network 102.Clients 110, 112, and 114 are clients of server 104 and server 106.Server 104 and server 106 may provide information, such as boot files,operating system images, and software applications to clients 110, 112,and 114. In this example, clients 110, 112, and 114 each represent anenvironment that hosts a plurality of service containers. A servicecontainer host environment may be, for example, a cloud environment, adata center environment, a rack of servers environment, or a singleserver environment.

Storage 108 is a network storage device capable of storing any type ofdata in a structured format or an unstructured format. In addition,storage 108 may represent a plurality of network storage devices.Further, storage 108 may store service configuration lists, servicecontainer dependency flow data, service container stub data, servicecontainer images, and the like. Furthermore, storage unit 108 may storeother types of data, such as authentication or credential data that mayinclude user names, passwords, and biometric data associated with systemadministrators, for example.

In addition, it should be noted that network data processing system 100may include any number of additional servers, clients, storage devices,and other devices not shown. Program code located in network dataprocessing system 100 may be stored on a computer readable storagemedium and downloaded to a computer or other data processing device foruse. For example, program code may be stored on a computer readablestorage medium on server 104 and downloaded to client 110 over network102 for use on client 110.

In the depicted example, network data processing system 100 may beimplemented as a number of different types of communication networks,such as, for example, an internet, an intranet, a local area network(LAN), and a wide area network (WAN). FIG. 1 is intended as an exampleonly, and not as an architectural limitation for the differentillustrative embodiments.

With reference now to FIG. 2, a diagram of a data processing system isdepicted in accordance with an illustrative embodiment. Data processingsystem 200 is an example of a computer, such as server 104 in FIG. 1, inwhich computer readable program code or instructions implementingprocesses of illustrative embodiments may be located. In thisillustrative example, data processing system 200 includes communicationsfabric 202, which provides communications between processor unit 204,memory 206, persistent storage 208, communications unit 210,input/output (I/O) unit 212, and display 214.

Processor unit 204 serves to execute instructions for softwareapplications and programs that may be loaded into memory 206. Processorunit 204 may be a set of one or more hardware processor devices or maybe a multi-processor core, depending on the particular implementation.Further, processor unit 204 may be implemented using one or moreheterogeneous processor systems, in which a main processor is presentwith secondary processors on a single chip. As another illustrativeexample, processor unit 204 may be a symmetric multi-processor systemcontaining multiple processors of the same type.

Memory 206 and persistent storage 208 are examples of storage devices216. A computer readable storage device is any piece of hardware that iscapable of storing information, such as, for example, withoutlimitation, data, computer readable program code in functional form,and/or other suitable information either on a transient basis and/or apersistent basis. Further, a computer readable storage device excludes apropagation medium. Memory 206, in these examples, may be, for example,a random access memory, or any other suitable volatile or non-volatilestorage device. Persistent storage 208 may take various forms, dependingon the particular implementation. For example, persistent storage 208may contain one or more devices. For example, persistent storage 208 maybe a hard drive, a flash memory, a rewritable optical disk, a rewritablemagnetic tape, or some combination of the above. The media used bypersistent storage 208 may be removable. For example, a removable harddrive may be used for persistent storage 208.

In this example, persistent storage 208 stores service containerdependency manager 218. However, it should be noted that even thoughservice container dependency manager 218 is illustrated as residing inpersistent storage 208, in an alternative illustrative embodimentservice container dependency manager 218 may be a separate component ofdata processing system 200. For example, service container dependencymanager 218 may be a hardware component coupled to communication fabric202 or a combination of hardware and software components.

Service container dependency manager 218 may run continually on dataprocessing system 200 as a daemon, for example. Service containerdependency manager 218 controls the process of breaking dependencebetween service containers. As an example, a Web application is deployedon an application server running on one service container (e.g.,container B) and the Web application depends on a database deployed on adatabase server running on another service container (e.g., containerA). In most of cases, the Web application will not start successfully orwill fail unless the database running on the other service container(container A) is ready to process service requests before the Webapplication is started. Typically, this type of service containerdependency is not a problem for legacy system environments astraditional distributed systems are not required to start and restartvery frequently. However, in a cloud environment, the operation ofcreating and removing service containers is used more often, especiallyfor multiple cloud users. Consequently, the dependency between servicecontainers and the time consumed while waiting for dependent servicecontainers to be up and running is considerable in a cloud computingenvironment.

Using the example above, service container dependency manager 218provides the requirements of both service containers A and B. Byutilizing service container dependency manager 218, a user of dataprocessing system 200 may start these two service containers A and B (ormore if needed) at the same time even though service container B isrequiring the service provided by container A. First, service containerB connects to service container dependency manager 218, then servicecontainer dependency manager 218 responds to service container B basedon a set of rules. The set of rules may include, for example: 1) ifservice container dependency manager 218 determines that the service oncontainer A is running and ready to process service requests, thenservice container dependency manager 218 forwards all service requestsfrom service container B directly to service container A; 2) if servicecontainer dependency manager 218 determines that service container A isnot started, then service container dependency manager 218 startsservice container A and responds to service requests from servicecontainer B using stub data corresponding to service container A runningon service container dependency manager 218; 3) if service containerdependency manager 218 determines that the service on container A is notstarted, then service container dependency manager 218 starts theservice on container A and responds to service requests from servicecontainer B using stub data corresponding to service container A runningon service container dependency manager 218; and 4) if service containerdependency manager 218 determines that service container A has failed,then service container dependency manager 218 takes over the serviceprovided by container A using stub data corresponding to servicecontainer A running on service container dependency manager 218 andrestarts service container A.

In other words, with service container dependency manager 218 running ondata processing system 200, a user can start all related servicecontainers at the same time, no matter what the relied upon servicecontainers or whether the services on those relied upon servicecontainers are started or not. Service container dependency manager 218handles all the service requests from service consumers and responds tothe service requests until the service on the relied upon container isready to process the service requests. As a result, service containerdependency manager 218 may decrease the time needed to deploy multipleservice containers having service container dependencies.

As a further example, assume that both container A and container B andtheir respective services are running correctly. However, servicecontainer dependency manager 218 determines that container A needs to beshutdown or that the service on container A needs to be restarted formaintenance. In this situation, service container dependency manager 218may take over the service provided by container A to implement zeroshutdown time from the server side.

In this example, service container dependency manager 218 includesservice monitor 220. Service container dependency manager 218 utilizesservice monitor 220 to monitor registered service containers within thehost environment. Service monitor 220 utilizes information withinservice configuration list 224 to determine which service containers tomonitor. Service configuration list 224 lists all registered servicecontainers within the host environment, along with their respectiveconfigurations and any corresponding service container dependencies.

Also in this example, service configuration list 224 includes servicecontainer dependency flow data 226, service container stub data 228,port number forwarding rule 230, and access rule 232. Service monitor220 monitors and records service container dependency flow data 226.Service container dependency flow data 226 represent informationregarding the flow of data between dependent service containers withinthe host environment.

Service container stub data 228 represent information corresponding toservice containers that are relied upon by dependent service containersin order for the dependent service containers to perform theirrespective services. Service container stub data 228 may include, forexample, an image, an image identifier, a port number identifier,service requests, and responses to the service requests corresponding todifferent service containers. Service container dependency manager 218may utilize service container stub data 228 to take over and execute aservice performed by a particular service container in response to thatparticular service container not being available to another servicecontainer that relies on a service provided by the unavailable servicecontainer.

Port number forwarding rule 230 is a rule that directs service containerdependency manager 218 to use service container stub data 228 when aservice container, which a running service container is dependent upon,is not running. Access rule 232 is a rule that directs service containerdependency manager 218 to allow direct access between a servicecontainer and its dependent service container when the service containeris running and ready to process service request from the dependentservice container.

Service monitor 220 also monitors and records service consumer requests234 and service provider responses 236. Service consumer requests 234represent service requests made by dependent service containers to otherservice containers that the dependent service containers rely upon tofunction. Service provider responses 236 represent responses to servicerequests provided by service containers to dependent service containers.Service monitor 220 stores service consumer requests 234 and serviceprovider responses 236 in service container stub data 228.

Communications unit 210, in this example, provides for communicationwith other computers, data processing systems, and devices via anetwork, such as network 102 in FIG. 1. Communications unit 210 mayprovide communications through the use of both physical and wirelesscommunications links. The physical communications link may utilize, forexample, a wire, cable, universal serial bus, or any other physicaltechnology to establish a physical communications link for dataprocessing system 200. The wireless communications link may utilize, forexample, shortwave, high frequency, ultra high frequency, microwave,wireless fidelity (Wi-Fi), bluetooth technology, global system formobile communications (GSM), code division multiple access (CDMA),second-generation (2G), third-generation (3G), fourth-generation (4G),4G Long Term Evolution (LTE), LTE Advanced, or any other wirelesscommunication technology or standard to establish a wirelesscommunications link for data processing system 200.

Input/output unit 212 allows for the input and output of data with otherdevices that may be connected to data processing system 200. Forexample, input/output unit 212 may provide a connection for user inputthrough a keypad, a keyboard, a mouse, and/or some other suitable inputdevice. Display 214 provides a mechanism to display information to auser and may include touch screen capabilities to allow the user to makeon-screen selections through user interfaces or input data, for example.

Instructions for the operating system, applications, and/or programs maybe located in storage devices 216, which are in communication withprocessor unit 204 through communications fabric 202. In thisillustrative example, the instructions are in a functional form onpersistent storage 208. These instructions may be loaded into memory 206for running by processor unit 204. The processes of the differentembodiments may be performed by processor unit 204 usingcomputer-implemented instructions, which may be located in a memory,such as memory 206. These program instructions are referred to asprogram code, computer usable program code, or computer readable programcode that may be read and run by a processor in processor unit 204. Theprogram instructions, in the different embodiments, may be embodied ondifferent physical computer readable storage devices, such as memory 206or persistent storage 208.

Program code 238 is located in a functional form on computer readablemedia 240 that is selectively removable and may be loaded onto ortransferred to data processing system 200 for running by processor unit204. Program code 238 and computer readable media 240 form computerprogram product 242. In one example, computer readable media 240 may becomputer readable storage media 244 or computer readable signal media246. Computer readable storage media 244 may include, for example, anoptical or magnetic disc that is inserted or placed into a drive orother device that is part of persistent storage 208 for transfer onto astorage device, such as a hard drive, that is part of persistent storage208. Computer readable storage media 244 also may take the form of apersistent storage, such as a hard drive, a thumb drive, or a flashmemory that is connected to data processing system 200. In someinstances, computer readable storage media 244 may not be removable fromdata processing system 200.

Alternatively, program code 238 may be transferred to data processingsystem 200 using computer readable signal media 246. Computer readablesignal media 246 may be, for example, a propagated data signalcontaining program code 238. For example, computer readable signal media246 may be an electro-magnetic signal, an optical signal, and/or anyother suitable type of signal. These signals may be transmitted overcommunication links, such as wireless communication links, an opticalfiber cable, a coaxial cable, a wire, and/or any other suitable type ofcommunications link. In other words, the communications link and/or theconnection may be physical or wireless in the illustrative examples. Thecomputer readable media also may take the form of non-tangible media,such as communication links or wireless transmissions containing theprogram code.

In some illustrative embodiments, program code 238 may be downloadedover a network to persistent storage 208 from another device or dataprocessing system through computer readable signal media 246 for usewithin data processing system 200. For instance, program code stored ina computer readable storage media in a data processing system may bedownloaded over a network from the data processing system to dataprocessing system 200. The data processing system providing program code238 may be a server computer, a client computer, or some other devicecapable of storing and transmitting program code 238.

The different components illustrated for data processing system 200 arenot meant to provide architectural limitations to the manner in whichdifferent embodiments may be implemented. The different illustrativeembodiments may be implemented in a data processing system includingcomponents in addition to, or in place of, those illustrated for dataprocessing system 200. Other components shown in FIG. 2 can be variedfrom the illustrative examples shown. The different embodiments may beimplemented using any hardware device or system capable of executingprogram code. As one example, data processing system 200 may includeorganic components integrated with inorganic components and/or may becomprised entirely of organic components excluding a human being. Forexample, a storage device may be comprised of an organic semiconductor.

As another example, a computer readable storage device in dataprocessing system 200 is any hardware apparatus that may store data.Memory 206, persistent storage 208, and computer readable storage media244 are examples of physical storage devices in a tangible form.

In another example, a bus system may be used to implement communicationsfabric 202 and may be comprised of one or more buses, such as a systembus or an input/output bus. Of course, the bus system may be implementedusing any suitable type of architecture that provides for a transfer ofdata between different components or devices attached to the bus system.Additionally, a communications unit may include one or more devices usedto transmit and receive data, such as a modem or a network adapter.Further, a memory may be, for example, memory 206 or a cache such asfound in an interface and memory controller hub that may be present incommunications fabric 202.

It is understood that although this disclosure includes a detaileddescription on cloud computing, implementation of the teachings recitedherein are not limited to a cloud computing environment. Rather,illustrative embodiments are capable of being implemented in conjunctionwith any other type of computing environment now known or laterdeveloped. Cloud computing is a model of service delivery for enablingconvenient, on-demand network access to a shared pool of configurablecomputing resources, such as, for example, networks, network bandwidth,servers, processing, memory, storage, applications, virtual machines,and services, which can be rapidly provisioned and released with minimalmanagement effort or interaction with a provider of the service. Thiscloud model may include at least five characteristics, at least threeservice models, and at least four deployment models.

The characteristics may include, for example, on-demand self-service,broad network access, resource pooling, rapid elasticity, and measuredservice. On-demand self-service allows a cloud consumer to unilaterallyprovision computing capabilities, such as server time and networkstorage, as needed automatically without requiring human interactionwith the service's provider. Broad network access provides forcapabilities that are available over a network and accessed throughstandard mechanisms that promote use by heterogeneous thin or thickclient platforms, such as, for example, mobile phones, laptops, andpersonal digital assistants. Resource pooling allows the provider'scomputing resources to be pooled to serve multiple consumers using amulti-tenant model, with different physical and virtual resourcesdynamically assigned and reassigned according to demand. There is asense of location independence in that the consumer generally has nocontrol or knowledge over the exact location of the provided resources,but may be able to specify location at a higher level of abstraction,such as, for example, country, state, or data center. Rapid elasticityprovides for capabilities that can be rapidly and elasticallyprovisioned, in some cases automatically, to quickly scale out andrapidly released to quickly scale in. To the consumer, the capabilitiesavailable for provisioning often appear to be unlimited and can bepurchased in any quantity at any time. Measured service allows cloudsystems to automatically control and optimize resource use by leveraginga metering capability at some level of abstraction appropriate to thetype of service, such as, for example, storage, processing, bandwidth,and active user accounts. Resource usage can be monitored, controlled,and reported providing transparency for both the provider and consumerof the utilized service.

Service models may include, for example, Software as a Service (SaaS),Platform as a Service (PaaS), and Infrastructure as a Service (IaaS).Software as a Service is the capability provided to the consumer to usethe provider's applications running on a cloud infrastructure. Theapplications are accessible from various client devices through a thinclient interface, such as a web browser (e.g., web-based e-mail). Theconsumer does not manage or control the underlying cloud infrastructureincluding network, servers, operating systems, storage, or evenindividual application capabilities, with the possible exception oflimited user-specific application configuration settings. Platform as aService is the capability provided to the consumer to deploy onto thecloud infrastructure consumer-created or acquired applications createdusing programming languages and tools supported by the provider. Theconsumer does not manage or control the underlying cloud infrastructureincluding networks, servers, operating systems, or storage, but hascontrol over the deployed applications and possibly application hostingenvironment configurations. Infrastructure as a Service is thecapability provided to the consumer to provision processing, storage,networks, and other fundamental computing resources where the consumeris able to deploy and run arbitrary software, which can includeoperating systems and applications. The consumer does not manage orcontrol the underlying cloud infrastructure, but has control overoperating systems, storage, deployed applications, and possibly limitedcontrol of select networking components, such as, for example, hostfirewalls.

Deployment models may include, for example, a private cloud, communitycloud, public cloud, and hybrid cloud. A private cloud is a cloudinfrastructure operated solely for an organization. The private cloudmay be managed by the organization or a third party and may existon-premises or off-premises. A community cloud is a cloud infrastructureshared by several organizations and supports a specific community thathas shared concerns, such as, for example, mission, securityrequirements, policy, and compliance considerations. The community cloudmay be managed by the organizations or a third party and may existon-premises or off-premises. A public cloud is a cloud infrastructuremade available to the general public or a large industry group and isowned by an organization selling cloud services. A hybrid cloud is acloud infrastructure composed of two or more clouds, such as, forexample, private, community, and public clouds, which remain as uniqueentities, but are bound together by standardized or proprietarytechnology that enables data and application portability, such as, forexample, cloud bursting for load-balancing between clouds.

A cloud computing environment is service oriented with a focus onstatelessness, low coupling, modularity, and semantic interoperability.At the heart of cloud computing is an infrastructure comprising anetwork of interconnected nodes.

With reference now to FIG. 3, a diagram illustrating a cloud computingenvironment is depicted in which illustrative embodiments may beimplemented. In this illustrative example, cloud computing environment300 includes a set of one or more cloud computing nodes 310 with whichlocal computing devices used by cloud consumers, such as, for example,personal digital assistant or a smart phone 320A, desktop computer 320B,laptop computer 320C, and/or automobile computer system 320N, maycommunicate. Cloud computing nodes 310 may be, for example, server 104and server 106 in FIG. 1. Local computing devices 320A-320N may be, forexample, clients 110-114 in FIG. 1.

Cloud computing nodes 310 may communicate with one another and may begrouped physically or virtually into one or more networks, such asprivate, community, public, or hybrid clouds as described hereinabove,or a combination thereof. This allows cloud computing environment 300 tooffer infrastructure, platforms, and/or software as services for which acloud consumer does not need to maintain resources on a local computingdevice, such as local computing devices 320A-320N. It is understood thatthe types of local computing devices 320A-320N are intended to beillustrative only and that cloud computing nodes 310 and cloud computingenvironment 300 can communicate with any type of computerized deviceover any type of network and/or network addressable connection using aweb browser, for example.

With reference now to FIG. 4, a diagram illustrating abstraction modellayers is depicted in accordance with an illustrative embodiment. Theset of functional abstraction layers shown in this illustrative examplemay be provided by a cloud computing environment, such as cloudcomputing environment 300 in FIG. 3. It should be understood in advancethat the components, layers, and functions shown in FIG. 4 are intendedto be illustrative only and embodiments of the invention are not limitedthereto. As depicted, the following layers and corresponding functionsare provided.

Abstraction layers of a cloud computing environment 400 includeshardware and software layer 402, virtualization layer 404, managementlayer 406, and workloads layer 408. Hardware and software layer 402includes the hardware and software components of the cloud computingenvironment. The hardware components may include, for example,mainframes 410, RISC (Reduced Instruction Set Computer)architecture-based servers 412, servers 414, blade servers 416, storagedevices 418, and networks and networking components 420. In someillustrative embodiments, software components may include, for example,network application server software 422 and database software 424.

Virtualization layer 404 provides an abstraction layer from which thefollowing examples of virtual entities may be provided: virtual servers426; virtual storage 428; virtual networks 430, including virtualprivate networks; virtual applications and operating systems 432; andvirtual clients 434.

In one example, management layer 406 may provide the functions describedbelow. Resource provisioning 436 provides dynamic procurement ofcomputing resources and other resources, which are utilized to performtasks within the cloud computing environment. Metering and pricing 438provides cost tracking as resources are utilized within the cloudcomputing environment, and billing or invoicing for consumption of theseresources. In one example, these resources may comprise applicationsoftware licenses. Security provides identity verification for cloudconsumers and tasks, as well as protection for data and other resources.User portal 440 provides access to the cloud computing environment forconsumers and system administrators. Service level management 442provides cloud computing resource allocation and management such thatrequired service levels are met. Service level agreement (SLA) planningand fulfillment 444 provides pre-arrangement for, and procurement of,cloud computing resources for which a future requirement is anticipatedin accordance with an SLA.

Workloads layer 408 provides examples of functionality for which thecloud computing environment may be utilized. Example workloads andfunctions, which may be provided by workload layer 408, may includemapping and navigation 446, software development and lifecyclemanagement 448, virtual classroom education delivery 450, data analyticsprocessing 452, transaction processing 454, and breaking dependencebetween service containers processing 456.

Illustrative embodiments provide a virtual service with a recorded stubof a service provider container running on a cloud environment toresolve dependency between a service consumer container and the serviceprovider container. As a result, the service consumer container does notneed to care about the service provider container's state. The virtualservice, which has the recorded stub of the service provider containerrunning on it, manages all service consumer requests and serviceprovider responses. Therefore, the virtual service decreases the serviceinitialization time and increases system performance.

A service monitor runs on the virtual service to monitor the networktraffic across the service containers. The service monitor records thenetwork traffic data and saves service request/response data in a stubof the service provider container. In addition, the service monitormaintains a service configuration list that includes source/targetservice container information, which is associated with the stub.Consequently, the virtual service automatically sets up servicecontainer dependency flow monitoring and recording across servicecontainers.

If information in the service configuration list matches informationcorresponding to a service consumer request to a service providercontainer, which is currently offline, then the virtual service respondsto the service consumer request using the stub corresponding to theservice provider's container. Thus, the virtual service leverages thestored stub of the service provider container to break the dependencebetween the service consumer container and the service providercontainer during initialization or start up of the service providercontainer. On the other hand, if the service provider container is upand running, then the virtual service forwards the service consumerrequest directly to the service provider container for processing.

Therefore, illustrative embodiments utilize service virtualization todecouple service container dependencies while service containers arestarting or restarting. Illustrative embodiments may generate multiplevirtual services running on existing networks instead of generating avirtual network. The virtualization of illustrative embodimentsvirtualizes Transmission Control Protocol/Hypertext Transfer Protocol(TCP/HTTP) communications across service containers, rather than thenetwork, itself.

Thus, illustrative embodiments may decrease service containerdeployment/start time, especially in a complex host environment. Inaddition, illustrative embodiments may provide zero down time forresponding to service requests in some circumstances. Further,illustrative embodiments may not require additional changes to eitherthe requesting application side or the service provider side.

With reference now to FIG. 5, a diagram illustrating an example of aservice container management system is depicted in accordance with anillustrative embodiment. Service container management system 500 may beimplemented in a network of data processing systems, such as networkdata processing system 100 in FIG. 1, or a cloud computing environment,such as cloud computing environment 300 in FIG. 3. Service containermanagement system 500 is a system of hardware and software componentsfor managing service container dependencies by breaking the dependencebetween linked service containers.

In this example, service container management system 500 includesservice container dependency manager 502, web application servicecontainer B 504, and database service container A 506. Service containerdependency manager 502 may be, for example, service container dependencymanager 218 in FIG. 2. At 508, service container dependency manager 502receives a service request from web application service container B 504.The service request received from web application service container B504 is requesting the database service provided by database servicecontainer A 506. In other words, web application service container B 504is a dependent service container that relies on a response from theservice provided by database service container A 506 in order to performits respective service.

Further, service container dependency manager 502 checks the servicestatus of database service container A 506 at 510. If the service statusindicates that database service container A 506 is running, then servicecontainer dependency manager 502 forwards the service request receivedfrom web application service container B 504 to database servicecontainer A 506 at 512. After receiving the service request, databaseservice container A 506 processes the service request and sends aresponse to the service request directly to web application servicecontainer B 504 at 514. If the service status at 510 indicates thatdatabase service container A 506 is not running, then service containerdependency manager 502 starts database service container A 506 at 516and sends a response to the service request received from webapplication service container B 504 at 518 using stub data correspondingto database service container A 506. The stub data may be, for example,service container stub data 228 in FIG. 2.

With reference now to FIG. 6, a diagram illustrating an example of ahost environment is depicted in accordance with an illustrativeembodiment. Host environment 600 may be implemented in a network of dataprocessing systems, such as network data processing system 100 in FIG.1, or a cloud computing environment, such as cloud computing environment300 in FIG. 3. In this example, host environment 600 includes servicecontainer dependency manager 602, service B in container B 604, andservice A in container A 606. However, it should be noted that hostenvironment 600 is only meant as an example and not as a limitation onillustrative embodiments. For example, host environment 600 may includemore service containers than illustrated. In addition, service containerdependency manager 602, service B in container B 604, and service A incontainer A 606 may be remotely distributed in a plurality of differenthost environments instead of being located within one host environment.

Service container dependency manager 602 may be, for example, servicecontainer dependency manager 502 in FIG. 5. Service B in container B 604may be, for example, web application service container B 504 in FIG. 5.Service A in container A 606 may be, for example, database servicecontainer A 506 in FIG. 5.

In this example, service container dependency manager 602 includesservice monitor 608 and service configuration list 610. Service monitor608 and service configuration list 610 may be, for example, servicemonitor 220 and service configuration list 224 in FIG. 2. Servicecontainer dependency manager 602 utilizes service monitor 608 to monitorand record activity between service B in container B 604, and service Ain container A 606. Service monitor 608 utilizes information in serviceconfiguration list 610 to know which service containers andcorresponding port numbers to monitor within host environment 600.

In this example, service monitor 608 monitors a start up eventcorresponding to service B in container B 604 at 612. Service containerdependency manager 602 allows direct sending of a service request fromservice B in container B 604 to service A in container A 606 at 614 ifservice A is up and running. Also, if no access rule exists in serviceconfiguration list 610 for service B in container B 604 to service A incontainer A 606, then service monitor 608 records the service requestfrom service B to service A and add the access rule for service B toservice A to service configuration list 610 at 616. In addition, servicecontainer dependency manager 602 forwards service requests from serviceB to service A at 618.

At 620, service monitor 608 monitors a shut down and restart event ofservice A in container A 606. At 622, service container dependencymanager 602 enables a port number forwarding rule to utilize stub datain service configuration list 610 when service A is not running. Thestub data may be, for example, service container stub data 228 in FIG.2. At 624, service container dependency manager 602 responds to theservice request from service B using the stub data running on servicecontainer dependency manager 602 when service A is shut down orrestarting.

With reference now to FIG. 7, a diagram illustrating an example of aservice monitor is depicted in accordance with an illustrativeembodiment. Service monitor 700 may be located in a host cloudenvironment, such as cloud computing environment 300 in FIG. 3. Inaddition, service monitor 700 may be implemented in a service containerdependency manager, such as service container dependency manager 602 inFIG. 6. For example, service monitor 700 may be service monitor 608 inFIG. 6.

In this example, at 702 service monitor 700 monitors new servicecontainers that start with a dependency link between service containers,such as the dependency link between service B in container B 604 andservice A in container A 606 in FIG. 6. In addition, at 704 servicemonitor 700 monitors new service containers that start with publishedand/or exposed port number parameters. For example, service monitor 700monitors all inbound service requests between service containers basedon the following rules: 1) if two service containers with “--name” and“--link” parameters are started on the host environment, then servicemonitor 700 monitors the current status (e.g., running or not running)of the service containers having the dependency link between the servicecontainers and monitors all exposed port numbers of the servicecontainers; 2) if a service container with an “--expose” parameter toexpose its corresponding port number is started on the host environment,then service monitor 700 queries a service configuration list todetermine which port number is exposed and needs to be monitored for theservice container; and 3) if a service container with a “--publish” or“--publish-all” parameter to publish its corresponding port numbers isstarted on the host environment, then, as with exposed port numbers,service monitor 700 can use the service configuration list to query thepublished port numbers of the service container.

With reference now to FIGS. 8A-8C, a flowchart illustrating a processfor managing service container dependency is shown in accordance with anillustrative embodiment. The process shown in FIGS. 8A-8C may beimplemented in a computer, such as, for example, server 104 FIG. 1, dataprocessing system 200 in FIG. 2, or a cloud computing node in cloudcomputing nodes 310 in FIG. 3.

The process begins when the computer starts a virtual service monitor ona host environment (step 802). The virtual service monitor may be, forexample, service monitor 608 in FIG. 6. The host environment may be, forexample, host environment 600 in FIG. 6.

The computer monitors service containers and their respective dependentservice containers that are included in a service configuration listcorresponding to the host environment using the virtual service monitor(step 804). The service configuration list may be, for example, serviceconfiguration list 610 in FIG. 6. Subsequently, the computer receives anotification from the virtual service monitor indicating that a firstservice container is running on the host environment (step 806). Thefirst service container may be, for example, web application servicecontainer B 504 in FIG. 5.

Afterward, the computer makes a determination as to whether the firstservice container is dependent on a second service container being upand running on the host environment (step 808). If the computerdetermines that the first service container is not dependent on a secondservice container being up and running on the host environment, nooutput of step 808, then the process returns to step 804 where thecomputer continues to monitor the service containers. If the computerdetermines that the first service container is dependent on a secondservice container being up and running on the host environment, yesoutput of step 808, then the computer makes a determination as towhether the second service container is running on the host environment(step 810). The second service container may be, for example, databaseservice container A 506 in FIG. 5.

If the computer determines that the second service container is notrunning on the host environment, no output of step 810, then the processproceeds to step 822. If the computer determines that the second servicecontainer is running on the host environment, yes output of step 810,then the computer makes a determination as to whether the serviceconfiguration list includes stub data corresponding to the secondservice container (step 812). The stub data corresponding to the secondservice container may be, for example, service container stub data 228in FIG. 2.

If the computer determines that the service configuration list does notinclude stub data corresponding to the second service container, nooutput of step 812, then the process proceeds to step 838. If thecomputer determines that the service configuration list does includestub data corresponding to the second service container, yes output ofstep 812, then the computer disables a port number forwarding rule thatuses the stub data corresponding to the second service container whenthe second service container is not running (step 814). The port numberforwarding rule may be, for example, port number forwarding rule 230 inFIG. 2. In addition, the computer passes service requests received fromthe first service container directly to the second service container(step 816). Thereafter, the process returns to step 804 where thecomputer continues to monitor the service containers using the virtualservice monitor.

The computer receives a notification from the virtual service monitorindicating that the second service container is not running on the hostenvironment (step 818). Afterward, the computer makes a determination asto whether a running service container is dependent on the secondservice container being up and running on the host environment based oninformation in the service configuration list (step 820). If thecomputer determines that no running service container depends on thesecond service container being up and running on the host environmentbased on the information in the service configuration list, no output ofstep 820, then the process returns to step 804 where the computercontinues to monitor the service containers using the virtual servicemonitor. If the computer determines that a running service container isdependent on the second service container being up and running on thehost environment based on the information in the service configurationlist, yes output of step 820, then the computer makes a determination asto whether the service configuration list includes stub datacorresponding to the second service container (step 822).

If the computer determines that the service configuration list does notinclude stub data corresponding to the second service container, nooutput of step 822, then the process proceeds to step 836. If thecomputer determines that the service configuration list does includestub data corresponding to the second service container, yes output ofstep 822, then the computer enables the port number forwarding rule touse the stub data corresponding to the second service container when thesecond service container is not running (step 824). Further, thecomputer starts the second service container on the host environment(step 826).

Furthermore, the computer responds to the service requests received fromthe first service container using the stub data corresponding to thesecond service container (step 828). Moreover, the computer makes adetermination as to whether the second service container is running onthe host environment (step 830). If the computer determines that thesecond service container is not running on the host environment, nooutput of step 830, then the process returns to step 828 where thecomputer continues to respond to the service requests received from thefirst service container using the stub data corresponding to the secondservice container. If the computer determines that the second servicecontainer is running on the host environment, yes output of step 830,then the computer disables the port number forwarding rule (step 832).In addition, the computer passes the service requests received from thefirst service container directly to the second service container (step834). Thereafter, the process returns to step 804 where the computercontinues to monitor the service containers using the virtual servicemonitor.

The computer starts the second service container on the host environment(step 836) in response to the computer determining that the serviceconfiguration list does not include stub data corresponding to thesecond service container. The computer also passes service requestsreceived from the first service container directly to the second servicecontainer that is starting (step 838). In addition, the computergenerates an access rule for the first service container to the secondservice container (step 840). The access rule may be, for example,access rule 232 in FIG. 2.

Further, the computer records the service requests from the firstservice container to the second service container (step 842).Furthermore, the computer makes a determination as to whether the secondservice container is running on the host environment (step 844). If thecomputer determines that the second service container is not running onthe host environment, no output of step 844, then the process returns tostep 842 where the computer continues to record the service requestsfrom the first service container to the second service container. If thecomputer determines that the second service container is running on thehost environment, yes output of step 844, then the computer generatesthe stub data corresponding to the second service container in theservice configuration list based on: a first image, first imageidentifier, and first port number identifier corresponding to the firstservice container; a second image, second image identifier, and secondport number identifier corresponding to the second service container;type of service requests received from the first service container tothe second service container; and response messages sent from the secondservice container to the first service container (step 846). Thereafter,the process returns to step 804 where the computer continues to monitorthe service containers using the virtual service monitor.

Thus, illustrative embodiments of the present invention provide acomputer-implemented method, computer system, and computer programproduct for breaking dependence between service containers in a hostenvironment using stub data running on a service container dependencymanager of the host environment. The descriptions of the variousembodiments of the present invention have been presented for purposes ofillustration, but are not intended to be exhaustive or limited to theembodiments disclosed. Many modifications and variations will beapparent to those of ordinary skill in the art without departing fromthe scope and spirit of the described embodiment. The terminology usedherein was chosen to best explain the principles of the embodiment, thepractical application or technical improvement over technologies foundin the marketplace, or to enable others of ordinary skill in the art tounderstand the embodiments disclosed here.

What is claimed is:
 1. A computer-implemented method for managingservice container dependency, the computer-implemented methodcomprising: receiving, by a computer, a notification that a firstservice container is running on a host environment; determining, by thecomputer, whether the first service container is dependent on a secondservice container being up and running on the host environment;responsive to the computer determining that the first service containeris dependent on the second service container being up and running on thehost environment, determining, by the computer, whether the secondservice container is running on the host environment; responsive to thecomputer determining that the second service container is not running onthe host environment, responding, by the computer, to service requestsfrom the first service container to the second service container usingstub data running on the computer that corresponds to the second servicecontainer; responsive to the computer determining that a running servicecontainer is dependent on the second service container being up andrunning on the host environment based on the information in a serviceconfiguration list, determining, by the computer, whether the serviceconfiguration list includes the stub data corresponding to the secondservice container; responsive the computer determining that the serviceconfiguration list does include the stub data corresponding to thesecond service container, enabling, by the computer, a port numberforwarding rule to use the stub data corresponding to the second servicecontainer when the second service container is not running; andstarting, by the computer, the second service container on the hostenvironment.
 2. The computer-implemented method of claim 1 furthercomprising: responsive to the computer determining that the secondservice container is running on the host environment, determining, bythe computer, whether the service configuration list includes the stubdata corresponding to the second service container; responsive to thecomputer determining that the service configuration list does includethe stub data corresponding to the second service container, disabling,by the computer, a port number forwarding rule that uses the stub datacorresponding to the second service container when the second servicecontainer is not running on the host environment; and passing, by thecomputer, the service requests from the first service container directlyto the second service container.
 3. The computer-implemented method ofclaim 1 further comprising: monitoring, by the computer, servicecontainers and their respective dependent service containers listed inthe service configuration list corresponding to the host environmentusing a service monitor.
 4. The computer-implemented method of claim 1further comprising: receiving, by the computer, a notificationindicating that the second service container is not running on the hostenvironment; and determining, by the computer, whether the runningservice container is dependent on the second service container being upand running on the host environment based on information in the serviceconfiguration list.
 5. The computer-implemented method of claim 1further comprising: generating, by the computer, an access rule for thefirst service container to the second service container.
 6. Thecomputer-implemented method of claim 1 further comprising: recording, bythe computer, the service requests from the first service container tothe second service container; and recording, by the computer, responsesto the service requests.
 7. The computer-implemented method of claim 1further comprising: responsive to the computer determining that thesecond service container is running on the host environment, generating,by the computer, the stub data corresponding to the second servicecontainer based on an image, an image identifier, and a port numberidentifier corresponding to the second service container, the servicerequests received from the first service container to the second servicecontainer; and responses to the service requests sent from the secondservice container to the first service container.
 8. Thecomputer-implemented method of claim 1, wherein the host environment isa cloud environment, and wherein the cloud environment includes thecomputer, the first service container, and the second service container.9. The computer-implemented method of claim 1, wherein the computerutilizes the stub data to take over and execute a service of the secondservice container in response to the second service container not beingavailable to process the service requests from the first servicecontainer which depends on the service of the second service container.10. A computer system for managing service container dependency, thecomputer system comprising: a bus system; a storage device connected tothe bus system, wherein the storage device stores program instructions;and a processor connected to the bus system, wherein the processorexecutes the program instructions to: receive a notification that afirst service container is running on a host environment; determinewhether the first service container is dependent on a second servicecontainer being up and running on the host environment; determinewhether the second service container is running on the host environmentin response to determining that the first service container is dependenton the second service container being up and running on the hostenvironment; respond to service requests from the first servicecontainer to the second service container using stub data running on thecomputer system that corresponds to the second service container inresponse to determining that the second service container is not runningon the host environment; determine whether the service configurationlist includes the stub data corresponding to the second servicecontainer in response to determining that a running service container isdependent on the second service container being up and running on thehost environment based on the information in a service configurationlist; enabling a port number forwarding rule to use the stub datacorresponding to the second service container when the second servicecontainer is not running in response to determining that the serviceconfiguration list does include the stub data corresponding to thesecond service container; and start the second service container on thehost environment.
 11. The computer system of claim 10, wherein theprocessor further executes the program instructions to: determinewhether the service configuration list includes the stub datacorresponding to the second service container in response to determiningthat the second service container is running on the host environment;disable a port number forwarding rule that uses the stub datacorresponding to the second service container when the second servicecontainer is not running on the host environment in response todetermining that the service configuration list does include the stubdata corresponding to the second service container; and pass the servicerequests from the first service container directly to the second servicecontainer.
 12. A computer program product for managing service containerdependency, the computer program product comprising a computer readablestorage medium having program instructions embodied therewith, theprogram instructions executable by a computer to cause the computer toperform a method comprising: receiving, by the computer, a notificationthat a first service container is running on a host environment;determining, by the computer, whether the first service container isdependent on a second service container being up and running on the hostenvironment; responsive to the computer determining that the firstservice container is dependent on the second service container being upand running on the host environment, determining, by the computer,whether the second service container is running on the host environment;responsive to the computer determining that the second service containeris not running on the host environment, responding, by the computer, toservice requests from the first service container to the second servicecontainer using stub data running on the computer that corresponds tothe second service container; responsive to the computer determiningthat a running service container is dependent on the second servicecontainer being up and running on the host environment based on theinformation in a service configuration list, determining, by thecomputer, whether the service configuration list includes the stub datacorresponding to the second service container; responsive the computerdetermining that the service configuration list does include the stubdata corresponding to the second service container, enabling, by thecomputer, a port number forwarding rule to use the stub datacorresponding to the second service container when the second servicecontainer is not running; and starting, by the computer, the secondservice container on the host environment.
 13. The computer programproduct of claim 12 further comprising: responsive to the computerdetermining that the second service container is running on the hostenvironment, determining, by the computer, whether the serviceconfiguration list includes the stub data corresponding to the secondservice container; responsive to the computer determining that theservice configuration list does include the stub data corresponding tothe second service container, disabling, by the computer, a port numberforwarding rule that uses the stub data corresponding to the secondservice container when the second service container is not running onthe host environment; and passing, by the computer, the service requestsfrom the first service container directly to the second servicecontainer.
 14. The computer program product of claim 12 furthercomprising: monitoring, by the computer, service containers and theirrespective dependent service containers listed in the serviceconfiguration list corresponding to the host environment using a servicemonitor.
 15. The computer program product of claim 12 furthercomprising: receiving, by the computer, a notification indicating thatthe second service container is not running on the host environment; anddetermining, by the computer, whether the running service container isdependent on the second service container being up and running on thehost environment based on information in the service configuration list.16. The computer program product of claim 12 further comprising:generating, by the computer, an access rule for the first servicecontainer to the second service container.
 17. The computer programproduct of claim 12 further comprising: recording, by the computer, theservice requests from the first service container to the second servicecontainer; and recording, by the computer, responses to the servicerequests.
 18. The computer program product of claim 12 furthercomprising: responsive to the computer determining that the secondservice container is running on the host environment, generating, by thecomputer, the stub data corresponding to the second service containerbased on an image, an image identifier, and a port number identifiercorresponding to the second service container, the service requestsreceived from the first service container to the second servicecontainer; and responses to the service requests sent from the secondservice container to the first service container.